The present invention relates to fuel oil heaters and, more particularly, to an electrical heater for improving the operation of a canister filter in the supply line for a fuel oil heater.
A large number of homes in the United States are presently heated by fuel oil systems. Such a system will typically include a storage tank for storing a large quantity of fuel oil which will be consumed by the system over a period of time, depending upon the severity of the weather. Although some storage tanks for home fuel oil heating systems are buried underground, it is common to provide an elevated storage tank above ground. With such an arrangement, no pump will be needed for supplying the fuel oil to the home; rather, the supply line from the tank into the home can be a gravity feed line. Such a line will often include a canister filter to remove particulate matter which may be suspended in the fuel oil.
Although fuel oil filters of this type generally operate effectively, severely cold weather will cause the fuel oil to become much more viscous. When this occurs, the oil in the supply line will not flow through the filter as easily as under normal operating conditions and the fuel oil may tend to thicken and congeal in the filter. A point may be reached in which the fuel oil supply to the home will be reduced below the level of that needed for operation of the fuel oil furnace. The flow of fuel oil through the filter may in fact stop completely if the temperature of the oil is reduced sufficiently.
In the past, it has been known to provide heat to fuel supply filters for various reasons. In U.S. Pat. No. 2,166,912, issued July 18, 1939, to Little, a fuel supply system for storing and supplying hydrocarbon gas, such as butane or propane, is provided with a gasifying unit which is connected to a buried supply tank. The gasifying unit heats the fuel as it is bubbled through a water compartment which cleanses it of tar and other foreign matter. The heater unit has a gas jet burner beneath the water compartment providing a source of heat.
In U.S. Pat. No. 2,397,142, issued Mar. 26, 1946, to Howard, a filter is disclosed having a series of burners positioned therebeneath which heat a fuel, such as gasoline, as the fuel is filtered. The fuel is filtered to remove lead particles from the gasoline and the heating causes such particles to precipitate out of the liquid fuel.
U.S. Pat. No. 2,250,903, issued July 29, 1941, to Browning, shows as in-ground butane supply tank in which a heating pipe passes a heated fluid through the tank to heat the butane stored in the tank.
A need exists, however, for a heating arrangement particularly configured to provide effective and efficient heat to a canister filter in a fuel oil heating system supply line to prevent the fuel oil passing therethrough from coagulating and retarding the flow of fuel to the system. Such a heating arrangement shold be simple, reliable, and provide an efficient source of heat to the filter. Additionally, it is desirable for such a heating arrangement to be relatively inexpensive to manufacture and to require little maintenance.